Analog self-interference cancellation systems for CMTS

Patent metadata

Field	Value
Publication number	US-10200076-B1
Application number	US-201816052458-A
Country	US
Kind code	B1
Filing date	Aug 1, 2018
Priority date	Aug 1, 2017
Publication date	Feb 5, 2019
Grant date	Feb 5, 2019

Abstract

A system for wired analog self-interference cancellation includes a coarse delayer that delays a sampled RF transmit signal by a first delay amount; a frequency downconverter that downconverts the sampled RF transmit signal to IF; a first canceller tap group comprising a first per-tap-group delayer, a first sampling coupler, a first per-tap delayer, and first and second analog vector modulators that generates an IF self-interference cancellation signal; a frequency upconverter that upconverts the IF self-interference cancellation signal to RF; and a receive coupler that combines the RF self-interference cancellation signal with the RF receive signal, reducing self-interference.

First claim

We claim:

1. A system for wired analog self-interference cancellation comprising:
a transmit coupler, communicatively coupled to a radio frequency (RF) transmit signal of a wired communication system, that samples the RF transmit signal to create a sampled RF transmit signal having an RF carrier frequency;
an analog-self-interference canceller comprising:
a first coarse delayer that delays the sampled RF transmit signal by a first delay amount, resulting in a delayed sampled RF transmit signal; wherein the first coarse delayer delays the sampled RF transmit signal prior to frequency downconversion;
a frequency downconverter, comprising a mixer, a local oscillator, and an intermediate frequency (IF) filter, wherein the frequency downconverter converts, by heterodyning, the delayed sampled RF transmit signal to a delayed sampled IF transmit signal having an IF carrier frequency, wherein the IF carrier frequency is less than the RF carrier frequency; and
a first canceller tap group comprising a first per-tap-group delayer, a first sampling coupler, a first per-tap delayer, first and second analog vector modulators, and a first combining coupler; wherein the first per-tap-group delayer further delays the delayed sampled IF transmit signal; wherein the first sampling coupler splits the delayed sampled IF transmit signal, after the first per-tap-group delayer, into first and second IF transmit signal components; wherein the first analog vector modulator generates a first IF self-interference cancellation signal component from the first IF transmit signal component; wherein the first per-tap delayer delays the second IF transmit signal component, resulting in a delayed second IF transmit signal component; wherein the second analog vector modulator generates a second IF self-interference cancellation signal component from the delayed second IF transmit signal component; wherein the first combining coupler combines the first and second IF self-interference cancellation signal components to generate an IF self-interference cancellation signal;

a frequency upconverter comprising a mixer, a local oscillator, and an RF filter, wherein the frequency upconverter converts, by heterodyning, the IF self-interference cancellation signal to an RF self-interference cancellation signal having the RF carrier frequency; and
a receive coupler, communicatively coupled to an RF receive signal of the wired communication system, that combines the RF self-interference cancellation signal with the RF receive signal, resulting in an RF composite receive signal; wherein the RF composite receive signal contains less self-interference than the RF receive signal.

2. The system of claim 1 , wherein the first coarse delayer comprises a discretely variable surface-acoustic-wave (SAW) delayer having a range of at least 1.5 microseconds.

3. The system of claim 2 , wherein the first coarse delayer has delay steps of at least 150 nanoseconds.

4. The system of claim 2 , wherein the first coarse delayer comprises a chain of amplified delays in series, each amplified delay of the chain coupled to a coarse delayer coupling point; wherein delays of the first coarse delayer are varied based on selection of first delayer coupling points.

5. The system of claim 4 , wherein the first per-tap-group delayer comprises a chain of bypassable delay blocks; wherein each of the bypassable delay blocks comprises an inductor-capacitor (LC) delay and an amplifier; wherein the bypassable delay blocks are binary encoded.

6. The system of claim 5 , wherein the first per-tap-group delayer has a base step of between one and ten nanoseconds.

7. The system of claim 5 , wherein the first per-tap delayer has a fixed delay.

8. The system of claim 5 , further comprising an analog self-interference canceller controller that adapts configuration parameters of the analog self-interference canceller based on at least one of transmit signal data, receive signal data, and environmental data; wherein the configuration parameters include tunable parameters of the first and second analog vector modulators and bypass settings of the first per-tap-group delayer.

9. The system of claim 8 , wherein the selection of first delayer coupling points is set based on measured drop distances between cable modem couplers coupled to the system.

10. The system of claim 8 , wherein the selection of first delayer coupling points is set automatically by the analog self-interference canceller controller based upon analysis of primary reflections observed at the system.

11. A system for wired analog self-interference cancellation comprising:
a transmit coupler, communicatively coupled to a radio frequency (RF) transmit signal of a wired communication system, that samples the RF transmit signal to create a sampled RF transmit signal having an RF carrier frequency;
an analog-self-interference canceller comprising:
a first coarse delayer that generates a first delayed sampled RF transmit signal by delaying the sampled RF transmit signal by a first delay amount and generates a second delayed sampled RF transmit signal by delaying the sampled RF transmit signal by a second delay amount; wherein the second delay amount is greater than the first delay amount; wherein the first coarse delayer generates delayed sampled RF transmit signals prior to frequency downconversion;
a frequency downconverter, comprising a mixer, a local oscillator, and an intermediate frequency (IF) filter, wherein the frequency downconverter converts, by heterodyning, the first and second delayed sampled RF transmit signals to first and second delayed sampled IF transmit signals having an IF carrier frequency, wherein the IF carrier frequency is less than the RF carrier frequency;
a first canceller tap group comprising a first per-tap-group delayer, a first sampling coupler, a first per-tap delayer, and first and second analog vector modulators; wherein the first per-tap-group delayer further delays the first delayed sampled IF transmit signal; wherein the first sampling coupler splits the first delayed sampled IF transmit signal, after the first per-tap-group delayer, into first and second IF transmit signal components; wherein the first analog vector modulator generates a first IF self-interference cancellation signal component from the first IF transmit signal component; wherein the first per-tap delayer delays the second IF transmit signal component, resulting in a delayed second IF transmit signal component; wherein the second analog vector modulator generates a second IF self-interference cancellation signal component from the delayed second IF transmit signal component;
a second canceller tap group comprising a second per-tap-group delayer, a second sampling coupler, a second per-tap delayer, and third and fourth analog vector modulators; wherein the second per-tap-group delayer further delays the second delayed sampled IF transmit signal; wherein the second sampling coupler splits the second delayed sampled IF transmit signal, after the second per-tap-group delayer, into third and fourth IF transmit signal components; wherein the third analog vector modulator generates a third IF self-interference cancellation signal component from the third IF transmit signal component; wherein the second per-tap delayer delays the fourth IF transmit signal component, resulting in a delayed fourth IF transmit signal component; wherein the fourth analog vector modulator generates a fourth IF self-interference cancellation signal component from the delayed fourth IF transmit signal component; and
a combining coupler that combines the first, second, third, and fourth IF self-interference cancellation signal components to generate an IF self-interfe

Assignees

• Kumu Networks Inc

Inventors

• Choi Jung-Il
• Hahn Wilhelm Steffen
• Jain Mayank

Classifications

• H04L27/38

  Demodulator circuits; Receiver circuits · CPC title

• H04B1/525

  with means for reducing leakage of transmitter signal into the receiver · CPC title

• H04L27/2691

  involving interference determination or cancellation · CPC title

• H04B1/0475

  with means for limiting noise, interference or distortion (H04B1/0483 takes precedence) · CPC title

• H04B1/44 Primary

  Transmit/receive switching · CPC title